Checkbox and radio buttons cannot be re-enabled in Safari 3

Description

Running Safari 3.0.4 on OS X 10.5.1

As reported in #2726, if you disable a radio button or check box and then try to re-enable it, clicking on the control still doesn't work. I put a logging statement in dijit.form.Button._onClick (right at the beginning). For enabled buttons this logging message appears... for disabled ones that have been re-enabled, it never gets into that method.

This behavior is easy to see on dijit/tests/form/test_CheckBox.html. Just click the enable button for cb7 and try clicking the button.